forensic glass analysis case study


Books for Industry, New York, 1974.

In general, the SWGMAT guideline recommends that reports contain enough administrative detail for a reader to determine the identities of all parties to the report and the nature of the request. Log in or sign up to add this lesson to a Custom Course. Alain Baxter Presented at the International Symposium on the Forensic Examination of Trace Evidence in Transition, San Antonio, Texas, June 24–28, 1996.

The Backward Fragmentation Pattern of Glass, As a Result of Impact from a Firearm Projectile. Before any samples are taken, the entire scene should be photographed in detail. AOAC, Gaithersburg, Maryland, 1990. Batten, R. A. 2. 1989). Glass composition analysis is performed infrequently in forensic laboratories for several reasons: Despite these drawbacks, chemical analysis remains the best means for differentiating glass specimens (Koons and Buscaglia 1999; Koons and Buscaglia 2002). ⇒⇒⇒ ⇐⇐⇐ has really great writers to help you get the grades you need, they are fast and do great research. Shirley McKie When glass fragments are introduced to the column, each will become suspended in the liquid at the level that is the same density as that glass fragment. 1983). Ryland, S. G. Sheet or container?—Forensic glass comparisons with an emphasis on source classification.

Environmental science 2002), because: Refractive index varies with wavelength of light and temperature (Bloss 1961). What does this mean for the overall investigation? FSS Report No. Petterd, C. I., Hamshere, J., Stewart, S., Brinch, K., Masi, T., and Roux, C. Glass particles in the clothing of members of the public in south-eastern Australia—A survey, Forensic Science International (1999) 103:193–198. If a suspect is found, samples should be taken from their clothing or hair for comparison.

Scientific Working Group for Materials Analysis (SWGMAT). Glass fragments can be transferred onto anything within this distance. The intensity of the light is proportional to the concentration of the atoms (Skoog and West 1980). Variability in refractive index across a 12-foot-wide ribbon of flat glass is approximately 0.0001 (Almirall 1996) to 0.0002 (Underhill 1980).

These methods include semiquantitative techniques such as scanning electron microscopy-energy dispersive spectrometry (Ryland 1986; Terry et al. Catterick, T. and Hickman, D. A.

vol. Davis, R. J. and DeHann, J. D. A survey of men’s footwear, Journal of the Forensic Science Society (1977) 17:271–285. The refractory materials lining the glass furnace are gradually eroded into the glass melt over the lifetime of the furnace. Scientific Working Group for Materials Analysis (SWGMAT). The two specimens have been shown to have different sources. Cassista, A. R. and Sandercock, P. M. L. Precision of glass refractive index measurements: temperature variation and double variation methods, and the value of dispersion, Canadian Society of Forensic Science Journal (1994) 27:203–208. To make matters worse, the junior investigator accidently, securely wipe the laptop’s entire hard drive. As with the Emmons double-variation method, fragments of glass are mounted in the previously calibrated, appropriate immersion liquid on a glass microscope slide and covered with a glass cover slip. De Rosa, R. L. and Condrate, R. A. Sr. Fourier-transform infrared spectroscopy studies for coatings, The Glass Researcher: Bulletin of Glass Science and Engineering (1999) 9:7–8. Roux, C., Kirk, R., Benson, S., Van Haren, T., and Petterd, C. I. Unfortunately, the junior forensic investigator who obtained a “forensic image” of the computer only performed a logical acquisition. The raw materials for glass manufacturing are first mixed together to form a batch and then melted in a furnace to produce liquid glass. Praxis Biology & General Science: What is a Living Thing? Koons, R. D. and Buscaglia, J. In the state of Western Australia it is illegal to access, own or distribute digital content relating to ‘cats’.Jane, the network administrator for the Daily Planet was reviewing network traffic logs when shenoticed that an employee may have been accessing digital content relating to cats. It provides good discrimination potential. An automated method for refractive index determination of glass fragments using a phase-contrast microscope, hot stage, and monochromatic light source has been published by ASTM [ASTM E1967-98(2003)]. 1976). Tor browser important artifacts from memory are collected. For small fragments, it is important to use containers that are not too large so that the glass doesn't bounce around and break further. 1988). Supplemental Requirements for the Accreditation of Forensic Science Testing and Calibration Laboratories. John Taylor If your assignment is submitted more than 5 days late, then you will be awarded a mark of 0 for the assignment. R. A. N. Publishers, Marietta, Ohio, 1994. A classification scheme for glass. But often, glass samples found at crime scenes are very small, so it's difficult to measure this parameter directly. Additional work in these areas is ongoing as advances are made and instrumentation improves. Select a subject to preview related courses: Refractive index (RI) is a unique property of any type of glass that can be used to compare a sample to a source, such as a broken window in someone's home.

(SWGMAT 2005a). Glass refractive index determination. Edmond Locard Law 241–247. In contrast to crystalline solids, which have an ordered internal arrangement of atoms, the internal structure of glass consists of a network of atoms lacking long-range symmetry. The aim of a comparative glass analysis is to exclude possible sources. The mere presence of fragments of glass on the clothing of an alleged burglar in a case involving entry through a broken window may be significant evidence if fragments are found.

A comprehensive running sheet of your actions in investigating the case study. Association of Official Analytical Chemists (AOAC). Of A Small Piece of Glass 1. Sandercock, P. M. L. Sample size considerations for control glass in casework, Canadian Society of Forensic Science Journal (2000) 33:173–185. During experimental studies, glass fragments have been recovered from up to four meters away from a breaking glass object (Francis 1993; Locke and Unikowski 1991). For glass, relative dispersion, or dispersive power, is used to quantify dispersion (Koons et al. The mixing of raw materials during batching is incomplete, and the batch will unmix during transport and delivery to the furnace. What did you do? Careers & Education; Case Studies; Contact Us; Case Studies. Wavelength dispersive detectors also are available for scanning electron microscopy-wavelength dispersive spectrometry (SEM-WDS) and can be used to produce quantitative data.

This fluorescence can be used as a basis to differentiate glass specimens (Lloyd 1981). A classification scheme for glass, Forensic Science International (1981) 17:265–281.

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